Dot printer and method for grey level recording with different bit-depth dimensions

Abstract

A non-impact recording apparatus for recording grey level exposures, the recording apparatus includes one or more recording elements such as LEDs. Image data signals of a predetermined multibits per pixel bit-depth dimension are generated by a data source along with a signal representing the predetermined bit-depth dimension. An exposure clock counter counts exposure clock pulses and outputs a count signal in response to clock pulses. The count signal represents a count value. A comparator compares a multibits-per-pixel image data signal with the count signal from the counter and generates a signal. A current driver is responsive to the signal from the comparator and controls a recording duration. Counting in the counter is adjusted in accordance with the multibits per pixel bit-depth dimension of the image data signal.

We claim: 
     
       1. A non-impact recording apparatus for recording grey level exposures of pixels with different bit-depth dimension, the recording apparatus comprising: a recording element;   means for providing first image data signals of a first predetermined multibits per pixel bit-depth dimension and for providing second image data signals of a second predetermined multibits per pixel bit-depth dimension;   means for providing a third signal representing the first bit-depth dimension and for providing a fourth signal representing the second bit-depth dimension;   an exposure clock counter means for counting exposure clock pulses and outputting a count signal in response to said clock pulses, said count signal representing a count value, said counter means being an up/down counter having a down and up-counting modes;   adjusting means responsive to said third signal for adjusting counting in said counter means in accordance with the multibits per pixel bit-depth dimension of said first image data signals to provide count values associated with the first bit-depth dimension and responsive to said fourth signal for adjusting counting in said counter means in accordance with the multibits per pixel bit-depth dimension of said second image data signals to provide count values associated with the second bit-depth dimension;   comparator means for comparing a multibits-per-pixel image dam signal with the count signal from said counter means and generating a signal; and   means responsive to said signal from said comparator means for controlling the recording element to control a recording duration.   
     
     
       2. The apparatus of claim 1 and wherein the counter means includes an n-stage count register and an m-stage count register wherein m and n are each whole numbers greater than one and said adjusting means generates a signal for switching between the down and up counting modes in accordance with the signal representing a current bit-depth dimension of operation. 
     
     
       3. The apparatus of claim 2 and including multiplexer means connected to the outputs of the n-stage and m-stage registers for outputting a combined count value. 
     
     
       4. A method for non-impact recording of grey level pixels, the method comprising the steps of: providing image data representing a pixel to be recorded, the image data for each pixel in one image being represented by signals having a first bit-depth dimension, and the image data for each pixel in a second image being represented by signals having a second bit-depth dimension, the first and second bit-depth dimensions being each greater than one and of different dimensions;   generating exposure clock pulses for timing an exposure duration;   counting exposure clock pulses in a counter and outputting a count signal in response to said clock pulses, said count signal representing a count value, said counter counting in down and up-counting modes;   adjusting a bit-depth dimension of said count signal output by said counter in accordance with the first or the second bit-depth dimension of said image data signal;   comparing a multibits-per-pixel image data signal with the count signal and generating a timing signal; and   in response to said timing signal controlling a recording element for a recording duration.   
     
     
       5. The method of claim 4 and wherein the counter includes an n-stage count register and an m-stage count register wherein m and n are each whole numbers greater than one and in the step of adjusting counting there is generated a signal for switching between the down and up counting modes in accordance with the signal representing a current bit-depth dimension of operation. 
     
     
       6. The method of claim 5 and wherein outputs of the n-stage and m-stage registers are multiplexed for outputting a combined count value. 
     
     
       7. A non-impact printhead for recording grey level exposures, the printhead comprising: a recording element;   means for storing image data signals of either a first or a second multibits per pixel bit-depth dimension;   means for receiving exposure clock pulses;   an up/down exposure clock counter means having down and up-counting modes for counting the exposure clock pulses and outputting a count signal representing a count value in response to said clock pulses, said counter means being operational in a first mode wherein a count signal is output by the counter means as a multibit signal having a first bit-depth dimension and in a second mode wherein a count signal is output by the counter means as a multibit signal having a second bit-depth dimension different than said first bit-depth dimension;   means connected to said counter means for receiving a first signal for selecting either a first or a second operating mode of the counter means;   means responsive to the first signal representing a selection of a bit-depth dimension for adjusting counting in said counter means in accordance with the multibits per pixel bit-depth dimension of the image data signals so that the bit-depth dimension of the counter means is identical to that of the image data signals.   comparator means for comparing a multibits-per-pixel image data signal with the count signal from said counter means and generating a second signal; and   means responsive to the second signal from said comparator means for controlling the recording element to control a recording duration.   
     
     
       8. The printhead of claim 7 and wherein the counter means includes an n-stage count register and an m-stage count register wherein m and n are each whole numbers greater than one and said means for adjusting counting generates a signal for switching between the down and up counting modes in accordance with the signal representing a current bit-depth dimension of operation. 
     
     
       9. The printhead of claim 8 and including multiplexer means connected to the outputs of the n-stage and m-stage registers for outputting a combined count value. 
     
     
       10. A driver chip for driving a recording element on a non-impact printhead for recording grey level exposures, the driver chip comprising: means for storing image data signals of either a first or a second multibits per pixel bit-depth dimension;   means for receiving exposure clock pulses;   an up/down exposure clock counter means having down and up-counting modes for counting the exposure clock pulses and outputting a count signal representing a count value in response to said clock pulses, said counter means being operational in a first mode wherein a count signal is output by the counter means as a multibit signal having a first bit-depth dimension and in a second mode wherein a count signal is output by the counter means as a multibit signal having a second bit-depth dimension different than said first bit-depth dimension;   means responsive to the first signal representing a selection of a bit-depth dimension for adjusting counting in said counter means in accordance with the multibits per pixel bit-depth dimension of the image data signals so that the bit-depth dimension of the counter means is the same as that of the image data signals;   means connected to said counter means for receiving a first signal for selecting either a first or the second operating mode of the counter means;   comparator means for comparing a multibits-per-pixel image data signal with the count signal from said counter means and generating a second signal; and   means responsive to the second signal from said comparator means for controlling the recording element to control a recording duration.   
     
     
       11. The driver chip of claim 10 and wherein the counter means includes an n-stage count register and an m-stage count register wherein m and n are each whole numbers greater than one and said means for adjusting counting generates a signal for switching between the down and up counting modes in accordance with the signal representing a current bit-depth dimension of operation. 
     
     
       12. The driver chip of claim 11 and including multiplexer means connected to the outputs of the n-stage and m-stage registers for outputting a combined count value.